Method backupPreImportRevision

db/import.go:454–487

backupPreImportRev attempts to make a temporary backup of a revision body if the revision is currently resident in the revision cache. This is the import parallel for the temporary revision bodies made during SG writes. Allows in-flight replications on other Sync Gateway nodes to serve the previou

(ctx context.Context, docid, revid string)

// other Sync Gateway nodes to serve the previous revision
// (https://github.com/couchbase/sync_gateway/issues/3740)
func (db *DatabaseCollectionWithUser) backupPreImportRevision(ctx context.Context, docid, revid string) error {

	// If Delta Sync is enabled, this will already be handled by the backup handling used for delta generation
	if db.deltaSyncEnabled() {
		return nil
	}

	previousRev, ok := db.revisionCache.Peek(ctx, docid, revid)
	if !ok {
		return nil
	}

	var kvPairs []base.KVPair
	if len(previousRev.Attachments) > 0 {
		kvPairs = append(kvPairs, base.KVPair{Key: BodyAttachments, Val: previousRev.Attachments})
	}

	if previousRev.Deleted {
		kvPairs = append(kvPairs, base.KVPair{Key: BodyDeleted, Val: true})
	}

	// Stamp _attachments and _deleted into backup
	oldRevJSON, err := base.InjectJSONProperties(previousRev.BodyBytes, kvPairs...)
	if err != nil {
		return err
	}

	setOldRevErr := db.setOldRevisionJSON(ctx, docid, revid, oldRevJSON, previousRev.Deleted, db.oldRevExpirySeconds(), previousRev.Channels)
	if setOldRevErr != nil {
		return fmt.Errorf("Persistence error: %v", setOldRevErr)
	}

	return nil
}

// ////// Import Filter Function